This year, two of our first three mares to foal experienced retained placentas–a placenta is considered retained if the mare does not expel it within three hours after birth. I always wait until the mare passes the placenta so that I can retrieve it for the foal check the next day. The vet will examine it to make sure no pieces remain in the mare’s uterus. Also, a retained placenta usually means a crampy mare who will pace and often roll, interfering with the foal’s effort to nurse.

After three hours of waiting and seeing no progress, I gave the first mare, Bunny, oxytocin to help stimulate uterine contractions. After the second shot she finally passed the placenta, over four hour after the birth. During the foal check the next day, the vet suggested that I monitor Bunny’s temperature for the next few days and put her on sulfa. Two days after the birth she spiked a fever. The vet cultured her and infused her with antibiotics for three days. The second mare, Ginger, again made no progress even with oxytocin. The vet made a late night call and manually removed the placenta. Because of our earlier experience with Bunny, we treated Ginger more aggressively right from the beginning.

When it came time to breed the mares, we let Bunny, who had the more virulent infection, go through her 30 day heat and bred her successfully on the next cycle. We bred Ginger on her 30 day heat and checked her infoal at fourteen days. This was the first year we have treated retained placenta so aggressively, and with such good results.

So I began to wonder about past years and if there was a relationship between retained placentas and breeding failures. I keep meticulous and detailed records of births and breeding. When I looked back at my 2010 breeding book, I found that the two mares who retained their placentas for more than three hours were the two mares who ended up open last year. Subsequent years proved to have similar results. My vet explained that a retained placenta becomes a breeding ground for bacteria in the uterus. Sometimes, as with Bunny the mare shows obvious signs of distress, but more often than not the mare may have a low grade infection that does not present with symptoms except a failed attempt to breed.

I’ve been breeding mares for almost ten years now, and I take every chance I can to learn about the science of breeding. But, invariably, I learn the most from observing my own mares, and keeping good records from year to year. Then I incorporate what I learn into my breeding practices. I have in the past attended a birth, made sure the foal was up and nursing well and then gone back to bed without waiting out the mare if it was late and she wasn’t making any progress on expelling her placenta. But after my experience with Bunny and Ginger this year, I realize how important thoughtful observation is to the success of my breeding program.